It is known to make anhydrides containing additional carboxylic acid moieties and dianhydrides of disubstituted maleic anhydrides by synthesis from simpler compounds. These are disclosed in commonly assigned U.S. Pat. Nos. 4,596,867 and 4,638,072, which are hereby fully incorporated by reference. It is also known to make polyimides from dianhydrides and aromatic amines. This is disclosed in U.S. Pat. No. 3,179,634 (1965). British Patent Specification No. 570,858 discloses various processes for making fiber-forming polymers.
In reviewing these references, it is clear that the preparation of anhydrides containing additional carboxylic acid moieties and dianhydrides of disubstituted maleic anhydrides by oxidation of substituted alkenes, i.e., diaryl maleic anhydrides, while retaining their alkene character, has not been contemplated in the prior art.
The general object of this invention is to provide novel compounds of maleic anhydride structure and novel derivatives of these compounds which are potentially difunctional in structure.